<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="lib/vue-2.4.0.js"></script>
</head>

<body>
    <div id="app">
        <input type="text" v-model="n1">

        <select name="" id="" v-model='opt'>
            <option value="+">+</option>
            <option value="-">-</option>
            <option value="*">*</option>
            <option value="/">/</option>
        </select>

        <input type="text" v-model="n2">

        <input type="button" value="=" @click="calc">

        <input type="text" v-model="result">
    </div>


    <script>
        // 创建 Vue 实例，得到 ViewModel
        var vm = new Vue({
            el: '#app',
            data: {
                n1: 0,
                n2: 0,
                result: 0,
                opt: '+'
            },
            methods: {
                calc() { // 计算器算数的方法  
                    // 逻辑：
                    switch (this.opt) {
                        case '+':
                            this.result = parseInt(this.n1) + parseInt(this.n2)
                            break;
                        case '-':
                            this.result = parseInt(this.n1) - parseInt(this.n2)
                            break;
                        case '*':
                            this.result = parseInt(this.n1) * parseInt(this.n2)
                            break;
                        case '/':
                            this.result = parseInt(this.n1) / parseInt(this.n2)
                            break;
                    }

                    // 注意：这是投机取巧的方式，正式开发中，尽量少用
                    // var codeStr = 'parseInt(this.n1) ' + this.opt + ' parseInt(this.n2)'
                    // this.result = eval(codeStr)
                }
            }
        });
    </script>
</body>

</html>